Muonium defect centers in single crystals were investigated as an analogue for atomic H impurities. A N-related muon level-crossing resonance was associated with a static center formed by trapping of a mobile Mu impurity at another defect. This trapped Mu was released above 800K. Muon spin depolarization data implied that both Mu0 and ground-state Mu+ centers were mobile. Strong correlations between growth of the trapped Mu resonance and Mu0 motion and transformation rates above 400K implied that Mu0 was the more likely precursor in that region.

Trapping of Mobile Mu Centers in Single Crystal AlN. R.L.Lichti, Y.G.Celebi, K.H.Chow, B.Hitti, S.F.J.Cox: Physica B, 2003, 340-342, 430-3